Radiation circuit hydraulic system for nuclear reactors and the like

ABSTRACT

A radiation circuit including a hydraulic system and comprising an activity generator, an irradiator, a tank for storing an activity carrier and a pump for the circulation of the activity carrier in the circuit, all interconnected by pipelines. The circuit is provided with a mixing chamber and an additional pump, the upper section of the mixing chamber communicating with the outlets of the activity generator and irradiator, and its lower section, through the pumps, with the inlets of the activity generator and irradiator. The chamber is arranged in a manner in which its upper section is below the lower portions of the activity generator and irradiator.

United States Patent [1 1 Gavar et a1.

[ Jan.14,1975

[ RADIATION CIRCUIT HYDRAULIC SYSTEM FOR NUCLEAR REACTORS AND THE LIKE22 Filed: Mar. 2, 1973 21 Appl. No.: 337,733

[52] US. Cl 250/430, 176/37, 250/432,

250/434, 250/497 [51] Int. Cl G21C 19/20 [58] Field of Search 250/428,430, 432, 435,

NUCLEAR GENERATOR [56] References Cited UNITED STATES PATENTS PrimaryExaminerHarold A. Dixon Attorney, Agent, or Firm-Waters, Roditi,Schwartz & Nissen [57] ABSTRACT A radiation circuit including ahydraulic system and comprising an activity generator, an irradiator, atank for storing an activity carrier and a pump for the circulation ofthe activity carrier in the circuit, all interconnected by pipelines.The circuit is provided with a mixing chamber and an additional pump,the upper section of the mixing chamber communicating with the outletsof the activity generator and irradiator, and its lower section, throughthe pumps, with the inlets of the activity generator and irradiator. Thechamber is arranged in a manner in which its upper section is below thelower portions of the activity generator and irradiator.

2 Claims, 1 Drawing Figure VACUUM PUMP l T IRRADlATOR MIXING CHAMBERAUXILIARY 2 IRRADIATOR TANK PAIENTED JAN I 4 I975 VACUUM/PUMP ZI 7Gllgiglq l IRRADIATOR 20 H I2 I5 AUXILIARY 6 -22 IRRADIATOR I 5 l4 TANKRADIATION CIRCUIT HYDRAULIC SYSTEM FOR NUCLEAR REACTORS AND THE LIKE Thepresent invention relates to sources of ionizing radiation, and moreparticularly to radiation circuits used as sources of radiation inscientific research or in industrial radiation processes (chemical,physical and biological).

Known in the art are radiation circuits which are used as sources forgamma radiation research nuclear reactors.

Such radiation circuits usually consist of an activity generator placedin proximity to the core of a nuclear reactor, an irradiator, a tank forstoring an activity carrier and a pump for the circulation of theactivity carrier (gamma carrier) in the circuit, all of these elementsbeing interconnected by pipelines. While passing through the activitygenerator, the gamma carrier becomes radioactive under the action ofneutrons emitted by the reactor and is then conveyed, through thepipelines to the irradiator where its gamma radiation is used to carryout radiation processes.

Following a shut-down of the radiation circuit, the gamma carrier mustbe drained off into a collector in order to provide an access to theirradiator and to prevent exposure of maintenance personnel toradiation.

In the known arrangements of radiation circuits, the gamma carrier isdrained off into the collector with the aid of remote control lockingdevices which are introduced into the circuit; while in other cases, inorder that the gamma carrier flow under the effect of gravity withoutthe formation of hydraulic pickets, one of the pipelines connecting theactivity generator to the irradiator being placed substantially higherthan the other.

A disadvantage of the known types of radiation circuits resides in thepresence of remote control locking devices which are generallyunreliable, especially when in contact with a corrosive activitycarrier. In radiation circuits, where locking devices are replaced by anupper and a lower pipelines connecting the activity generator to theirradiator, the upper pipeline requires a separate biological shielding,which renders the circuit complicated and expensive.

As a rule, the known circuits each have one activity generator and oneirradiator. An increase in the number of activity generators andirradiators in these radiation circuits is only possible through theintroduction of mechanical locking devices. The latter are renderedunreliable in operation under conditions of prolonged intensiveradiation and chemical activity of the gamma carrier, which may put theradiation circuit out of action for extensive periods of time.

It is an object of the present invention to provide a radiation circuithaving a hydraulic system without the need for mechanical lockingdevices, with pipelines connecting the activity generator and theirradiator being incorporated into a common biological shielding, and inwhich gravity drainage of the activity carrier is ensured when theradiation circuit is shut off, without causing the formation ofhydraulic pockets.

Another object of the invention is to provide a a radiation circuithaving a hydraulic system for the inclusion which allows of additionalirradiators without the introduction of ancillary mechanical lockingdevices.

These objects of the invention are attained in that a radiation circuitincluding a hydraulic system and comprising an activity generator, anirradiator, a tank for storing an activity carrier and a pump for thecircula' tion of the activity carrier in the circuit, which are allinterconnected by pipelines, is provided, with a mixing chamber and anadditional pump, the upper section of the former communicating with theoutlets of the activity generator and the irradiator, and its lowersection communicating through the pumps with the inlets of the activitygenerator and the irradiator, the mixing chamber being arranged so thatits upper section is located below the lower portions of the activitygenerator and the irradiator.

It is expedient that the radiation circuit be provided with at least oneadditional irradiator and additional pump, the irradiators inletcommunicating through the additional pump with the lower section of themixing chamber, and its outlet with the upper section of the mixingchamber.

The radiation circuit constructed according to the present invention,eliminates the need for any potentially unreliable mechanical lockingdevices, has a common biological shielding of the pipelines connectingthe activity generator to the irradiator and, upon shutdown for thecircuit, ensures the reliable dumping of the activity carrier into thecollector without the formation of so-called hydraulic pockets.

Another advantage of the radiation circuit constructed in accordancewith the present invention lies in that several irradiators can besimultaneously attached thereto or different successive or seriesirradiators without the necessity of introducing mechanical lockingdevices into the circuits hydraulic system.

The invention will now be explained in greater detail with reference toa description of a specific embodiment thereof and to the single FIGUREof the accompanying drawing representing a diagram of the radiationcircuit according to the invention.

The radiation circuit represented in the drawing comprises an activitygenerator ll having an outlet connected through a pipeline 2 to an.inlet in the upper section of a mixing chamber 3, and the inlet ofactivity generator 1, through an electromagnetic pump 4 and a pipeline5, to an outlet in the lower section of the mixing chamber 3. Thepipelines 2 and 5 are conducted through into a common biologicalshielding 6. The radiation circuit also comprises an irradiator 7 whoseoutlet is connected through a pipeline 8 to the upper section of themixing chamber 3, and an inlet of the irradiator, through anelectromagnetic pump 9 and a pipeline 10 to an outlet in such as a lowersection of the chamber 3. The pipelines 8 and 9 are conducted through acommon biological shielding 11. An additional irradiator 12 is connectedin a similar way, through pipelines 13 and 14 which are conductedthrough a common biological shielding 15, and a third electromagneticpump 16, to the mixing chamber 3. A tank 17 containing an activitycarrier, the gamma carrier 18, communicates with the lower section ofthe mixing chamber 3 through a pipeline l9 and with the upper section ofthe mixing chamber 3, via a pipeline 20. The pipeline 20 allows formaintaining vacuum in the entire radiation circuit by means of a singlevacuum pump 21 connected to the tank 17 through a pipeline 22. Themaintenance of vacuum is needed to prevent penetration of gas bubblesinto the pipelines 2, 5, 8, l0, 13, 14, 19, 20 and 22 and theelectromagnetic pumps 4, 9 and 16 and also to isolate the gamma carrier18 from atmospheric air.

The activity generator comprises a coiled pipe (not shown) placed in thereflector of a nuclear reactors core (not shown), so that neutronradiation activates the circulating gamma carrier 18. The latter is aliquid metal alloy of indium, gallium and tin with a melting point of11C. Other gamma carriers can also be employed, for example,indium-gallium, indium-bismuth alloys, or pure indium. The irradiators 7and 12 serving for the concentration of the radioactive gamma carrierare usually vessels whose shape is selected depending upon a particularradiation process. Thus, for research purposes, the irradiator can bemade as a closed cylinder with an internal coaxial channel which ensuresa highly intensive gamma radiation. The pumps 4, 9 and 16 may beelectromagnetic pumps of any type which develop sufficient pressure forthe circulation of the gamma carrier in the radiation circuit and whichare designed to operate under radiation conditions. The mixing chamber 3is a sufficiently long section of a pipeline (having a length-diameterratio of wherein complete mixing of the gamma carrier 18 is carried outupon arriving from the activity generator 1 and the irradiators 7 and12.

The mixing chamber 3 is positioned in such a way that its upper sectionlies below the lower portions of the activity generator 1 and theirradiators 7 and 12 so as to ensure the gravity drainage of the gammacarrier 18 upon a shut-down of the radiation circuit.

The tank 17 should contain the entire amount of the gamma carrier 18.All of the components of the radiation circuit should be made of amaterial having a high degree of chemical stability and radiationresistance, for example, stainless steel.

The foregoing example applies to a radiation circuit with one additionalirradiator 12. If required, more ad ditional irradiators may beconnected to the same radiation circuit in a manner similar to that ofthe irradiator 12.

The radiation circuit operates as follows.

Prior to commencing operation of the circuit, the gamma carrier 18 issupplied to the tank 17. Following the switching on of the pump 4, thegamma carrier 18 is fed from the tank 17 through the pipeline 19 to themixing chamber 3 and then, through the pipeline 5, to the generator 1.Under the action of the neutron radiation of the nuclear reactor, thegamma carrier 18 in the generator 1 becomes activated and arrives to themixing chamber 3. Upon the switching on of the pump 9, the active gammacarrier 18 is fed from the mixing chamber 3 through the pipeline 10 tothe irradiator 7 where radioactive decay of the nuclei of the gammacarrier 18 takes place, setting up a gamma field in the surroundingspace. From the irradiator 7, the gamma carrier 18 is returned throughthe pipeline 8 to the mixing chamber 3 from which the pump 4 againforces it through the pipeline 5 to the generator 1 for activation inthe next cycle.

As the half-life period of indium, the basic radioactive element in thegamma carrier, is equal to 54 min, the radiation circuit reaches itsrated power 2.5 to 3 hours after starting.

The additional irradiator is actuated by switching on theelectromagnetic pump 16. This results in an automatic redistribution ofthe radiation power produced in the radiators 7 and 12. In this case,the total radiation power of both the radiator 7, and the radiator 12exceeds that of the radiator 7 with the additional irradiator 12 thenbeing made non-operative.

The rate of the circulation of the gamma carrier 18 by the pumps 4, 9and 16 is to ensure a complete circulation of the gamma carrier 18 inone cycle over a period of time less than the half-life period ofindium, the basic radioactive element.

A radiation circuit with a power of 2 mW in the inner channel of thecylindrical irradiator 7 installed in a research nuclear reactor at thePhysics Institute of the Academy of Sciences of the Latvian SovietSocialist Republic generates a gamma field with an intensity of 5,000 -ylsec. A loss of radiation power of the irradiator is negligible, ascompared to a radiation circuit without a mixing chamber, and amountsonly to 2 3 percent.

A shut-down of the circuit is effected through switching off the pumps4, 9 and 16. The circulation of the gamma carrier 18 is then stopped andit flows by gravity into the tank 17.

What is claimed is:

1. A radiation circuit comprising an activity generator; an irradiator;a mixing chamber arranged so that its upper section is below the lowerparts of the activity generator and irradiator; an activity carrier; atank for storing said activity carrier communicating with said mixingchamber; two pumps for the circulation of said activity carrier; theupper section of said mixing chamber communicating with the outlets ofsaid activity generator and irradiator; the lower section of said mixingchamber communicating through one of said pumps with the inlets of saidactivity generator and through other said pump, with the inlet of saidirradiator.

2. A radiation circuit as claimed in claim 1, which is provided with atleast one additional irradiator and one additional pump, the additionalirradiators inlet communicating through the additional pump with thelower section of said mixing chamber and its outlet communi-

1. A radiation circuit comprising an activity generator; an irradiator;a mixing chamber arranged so that its upper section is below the lowerparts of the activity generator and irradiator; an activity carrier; atank for storing said activity carrier communicating with said mixingchamber; two pumps for the circulation of said activity carrier; theupper section of said mixing chamber communicating with the outlets ofsaid activity generator and irradiator; the lower section of said mixingchamber communicating through one of said pumps with the inlets of saidactivity generator and through other said pump, with the inlet of saidirradiator.
 2. A radiation circuit as claimed in claim 1, which isprovided with at least one additional irradiator and one additionalpump, the additional irradiator''s inlet communicating through theadditional pump with the lower section of said mixing chamber and itsoutlet communicating with the upper section of said chamber.